JP2009241359A - Multilayer film and packaging bag using this film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer film excellent in both heat-sealing strength and gas barrier properties, and to provide a packaging bag using this film. <P>SOLUTION: On at least one side of a base material layer comprising thermoplastic resin, there are successively laminated a gas barrier layer which is formed by coating with a dispersion liquid containing inorganic layer-like compound and water-soluble polymer, an overcoat layer containing cationic resin and hydroxyl group-contained resin, an adhesive layer, and a sealant layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer film and a packaging bag using the film.

  Conventionally, films made of thermoplastic resins such as polypropylene, polyester, polyamide, etc., due to their excellent mechanical properties, heat resistance, transparency, etc., in many fields such as food field, cosmetic field, agricultural chemical field, medical field, Widely used as packaging material.

  When a thermoplastic resin film is used as a packaging material, the film is often required to have gas barrier properties in order to prevent the contents from being deteriorated by oxygen. Moreover, in order to use as a packaging bag, these thermoplastic resin films are required to have heat seal strength.

As packaging materials having such a gas barrier property, the following techniques are being studied.
Patent Document 1 discloses a packaging material in which a base film, a gas barrier layer containing an inorganic layered compound and a resin, a protective layer containing polyurethane and an isocyanate-based compound, and a sealant film are laminated in this order. Yes.

  Patent Document 2 discloses a packaging in which a gas barrier layer containing a synthetic resin and an inorganic stratiform compound, a cured resin layer containing an unsaturated acid and a polyamine, and a heat seal layer are laminated in this order on one surface of a base film. The body is disclosed.

  In Patent Document 3, an undercoat layer, a gas barrier layer containing an inorganic layered compound and a water-soluble polymer, and an overcoat layer containing an acrylic resin and an isocyanate compound are laminated in this order on one side of a base film. A laminated body is disclosed.

  Patent Document 4 has a gas barrier layer formed by coating a dispersion containing an inorganic layered compound having an aspect ratio of 200 to 3000 and polyvinyl alcohol on one side of a base material layer, and an isocyanate compound, A multilayer film having a layer formed by applying a coating solution containing an active hydrogen compound and polyoxycarboxylic acid is disclosed.

Patent Document 5 discloses a gas barrier film in which a gas barrier layer containing an inorganic layered compound, a water-soluble polymer, and an amine compound having a specific composition is provided on at least one side of a substrate.
Japanese Patent Laid-Open No. 11-171237 JP 2000-355080 A JP 2001-80003 A JP 2005-220154 A Japanese Patent Laid-Open No. 10-166516

  However, in Patent Documents 1 to 4, since the cross-linked layer (adhesive layer) is directly laminated on the gas barrier layer containing the layered compound, the stress generated in the film cannot be sufficiently relaxed and used as a bag. In some cases, the heat seal strength may be insufficient.

  Further, in Patent Document 5, a resin having an amino group is used. However, since a cross-linked layer (adhesive layer) is directly laminated on the gas barrier layer, the stress generated in the film can be sufficiently relaxed. However, when used as a bag, the heat seal strength may be insufficient. Further, according to the study by the present inventors, it has been confirmed that when a resin having a hydroxyl group and a resin having an amino group are used in combination as the gas barrier layer, the gas barrier property is deteriorated.

  Therefore, the present invention provides a multilayer film excellent in both heat seal strength and gas barrier properties and a packaging bag using the film.

The gist of the present invention is as follows.
(1) A gas barrier layer formed by applying a dispersion containing an inorganic layered compound and a water-soluble polymer on at least one surface of a base material layer composed of a thermoplastic resin, a cationic resin, A multilayer film comprising an overcoat layer containing a hydroxyl group-containing resin, an adhesive layer, and a sealant layer sequentially laminated.

  (2) The multilayer film according to (1), wherein the overcoat layer does not contain a curing agent that reacts with a cationic resin.

  (3) The multilayer film of (1) or (2), wherein the cationic resin contained in the overcoat layer contains a primary amine.

  (4) The overcoat layer contains 5 to 100 parts by mass of a hydroxyl group-containing resin with respect to 100 parts by mass of the cationic resin, and any one of (1) to (3) Multilayer film.

  (5) The multilayer film according to any one of (1) to (4), wherein the resin having a hydroxyl group contained in the overcoat layer is polyvinyl alcohol or modified polyvinyl alcohol.

  (6) The multilayer film according to any one of (1) to (5), wherein the cationic resin contained in the overcoat layer is polyallylamine or chitosan.

  (7) The multilayer film according to any one of (1) to (6), wherein an anchor coat layer is provided between the base material layer and the gas barrier layer.

  (8) The multilayer film according to any one of (1) to (7), wherein the water-soluble polymer contained in the gas barrier layer contains at least one of a hydroxyl group and a carboxyl group.

  (9) The multilayer film according to any one of (1) to (8), wherein the adhesive layer contains an isocyanate.

(10) The multilayer film according to any one of (1) to (9), wherein the oxygen permeability at 20 ° C. and 50% RH is 20 ml / m ² · day · MPa or less.

  (11) A packaging bag comprising the multilayer film of any one of (1) to (10) above.

  Since the multilayer film of the present invention and the packaging bag using the same film are those in which an adhesive layer is formed on the gas barrier layer via an overcoat layer, the stress generated in the film can be sufficiently relaxed, Not only can a sufficient heat seal strength be achieved, but gas barrier properties are not lowered. For this reason, it can be excellent in heat seal strength and gas barrier properties.

  The multilayer film of the present invention comprises a gas barrier layer formed by coating a dispersion containing an inorganic layered compound and a water-soluble polymer on at least one surface of a base material layer composed of a thermoplastic resin. A film in which an overcoat layer, an adhesive layer, and a sealant layer are laminated in this order. Depending on the type of thermoplastic resin used for the base material layer, it is preferable to provide an anchor coat layer between the base material layer and the gas barrier layer.

  Examples of the thermoplastic resin used as the base layer in the present invention include polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; polylactic acid And biodegradable resins such as polybutylene succinate; polyolefin resins such as polypropylene and polyethylene; and mixtures thereof. A base material layer can be comprised with the film which consists of the said resin, or the laminated body of those films. This film may be an unstretched film or a stretched film.

  When producing a film, the thermoplastic resin is heated and melted with an extruder and extruded from a T die, and cooled and solidified with a cooling roll to obtain an unstretched film, or extruded from a circular die and cooled with water or air. Solidify to obtain an unstretched film. In the case of producing a stretched film, a method in which the unstretched film is wound up once or continuously with the production of the unstretched film is preferably stretched by a simultaneous biaxial stretching method or a sequential biaxial stretching method. From the viewpoint of performance such as mechanical properties and thickness uniformity of the film, it is preferable to combine the flat film forming method using a T die and the tenter stretching method. In order to improve coatability, it is preferable to perform a known surface treatment such as corona treatment or plasma treatment after film formation.

  In the multilayer film of the present invention, an anchor coat layer is provided between the base material layer and the gas barrier layer as described above in order to improve the film forming property of the gas barrier layer and the adhesion between the base material layer and the gas barrier layer. Can be provided. In that case, the material of the anchor coat layer may be appropriately selected depending on the type of the base material layer and the gas barrier layer, and is not particularly limited. However, polyurethane-based, polyester-based, acrylic rubber-based, titanate-based anchor coat agents, etc. A known anchor coating agent can be used. Furthermore, a wetting agent may be added to the anchor coating agent in order to adapt to a wide range of plastic material substrates.

  As the water-soluble polymer that forms the gas barrier layer, a known water-soluble polymer used for imparting gas barrier properties can be used. Usually, it contains at least one of a hydroxyl group and a carboxyl group.

  Examples of the water-soluble polymer containing a hydroxyl group include polyvinyl alcohol, modified polyvinyl alcohol, and saccharides. Examples of the modified polyvinyl alcohol include an ethylene-vinyl alcohol copolymer, polyvinyl alcohol modified with a carbonyl group, an ether group, a carboxylic acid, and the like. Of these, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferable.

  When using modified polyvinyl alcohol, the saponification degree is preferably 80% or more, more preferably 95% or more, and even more preferably 98% or more from the viewpoint of gas barrier properties. The degree of polymerization of the modified polyvinyl alcohol is preferably in the range of 100 to 5000, and more preferably in the range of 200 to 3000.

  Examples of the water-soluble polymer containing a carboxyl group include poly (meth) acrylic acid; maleic acid copolymers such as ethylene-maleic acid copolymer, isobutylene-maleic acid copolymer, and methyl vinyl ether-maleic acid copolymer; And polyitaconic acid. When these water-soluble polymers having a carboxyl group are used, it is preferable from the viewpoint of gas barrier properties to use the above-mentioned resin having a hydroxyl group in combination. In the case of using a water-soluble polymer having a carboxyl group and a water-soluble polymer having a hydroxyl group, the preferred mass ratio of both is (water-soluble polymer having a carboxyl group) / (water-soluble polymer having a hydroxyl group) = 90 / 10 to 10/90, more preferably 70/30 to 30/70, and still more preferably 70/30 to 50/50. Further, it is preferable to partially neutralize the carboxyl group with an alkali compound such as sodium hydroxide or magnesium hydroxide or a salt thereof. Specifically, it is preferable to neutralize 5 to 50 mol% of carboxyl groups, and more preferably to neutralize 10 to 30 mol% of carboxyl groups.

  These water-soluble polymers can be modified as long as the object of the present invention is not hindered, and known additives may be added. In particular, when a chelate compound such as a titanium chelate compound, a zirconium chelate compound, or an aluminum chelate compound is added, the hot water resistance can be increased. The addition ratio of these additives is preferably 10 parts by mass or less with respect to 100 parts by mass of the water-soluble polymer.

  As the inorganic layered compound that forms the gas barrier layer, a clay mineral having swelling property and cleavage property to a solvent can be particularly preferably used. Such clay minerals include kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, pyrophyllite, montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite hectorite, tetrasilic mica, sodium tenio. Light, muscovite, margarite, talc, vermiculite, phlogopite, xanthophyllite, chlorite and the like. Among these, smectite group, vermiculite group, and mica group clay minerals are preferable, and the smectite group is particularly preferable. Examples of the smectite group include montmorillonite, beidellite, nontronite, saponite, soconite, stevensite, and hectorite. However, it is not particularly limited. In addition, those obtained by treating these clay minerals with an organic substance such as ion exchange to improve dispersibility can also be used as the inorganic layered compound.

  The aspect ratio of the inorganic layered compound is preferably 200 to 3000. When the aspect ratio of the inorganic layered compound is too small, the gas barrier property tends to be insufficient. On the other hand, when the aspect ratio is too large, it is difficult to swell and cleave, and the gas barrier property tends to be insufficient. The inorganic layered compound preferably has an average particle size of 5 μm or less from the viewpoint of gas barrier properties, transparency, and film-forming properties. Particularly in applications where transparency is required, the average particle size is preferably 1 μm or less.

  Examples of the dispersion medium for swelling and cleaving the inorganic layered compound include water, alcohols (methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, etc.), dimethylformamide, dimethyl sulfoxide, acetone and the like. In particular, water, alcohol, and a water-alcohol mixture are preferable.

  In order to form the gas barrier layer, it is preferable to use a dispersion of an inorganic layered compound and a water-soluble polymer. The contents of the inorganic layered compound and the water-soluble polymer in this dispersion are not particularly specified, but from the viewpoint of coating properties, the total amount of the water-soluble polymer and the inorganic layered compound in the dispersion is Usually, it is preferably 0.1 to 70% by mass, and more preferably 1 to 20%. From the viewpoint of gas barrier properties, the mass ratio of the inorganic layered compound is preferably 3 to 70% by mass when the total amount of the inorganic layered compound and the water-soluble polymer is 100% by mass.

  The dispersion containing the inorganic layered compound and the water-soluble polymer can be obtained using a known apparatus such as a homogenizer. However, it is preferable from the viewpoint of dispersibility of the inorganic layered compound that high-pressure dispersion treatment is performed using a high-pressure dispersion apparatus.

  The overcoat layer is formed on the gas barrier layer containing the inorganic layered compound and the water-soluble polymer, but needs to contain a cationic resin and a resin having a hydroxyl group. By providing such an overcoat layer and then providing a sealant layer via an adhesive layer, a multilayer film having excellent heat seal strength can be obtained. The film is blocked only by including the cationic resin, and the required heat seal strength cannot be obtained only by including the resin having a hydroxyl group.

  The cationic resin contained in the overcoat layer includes a resin having a tertiary amine such as a methyldiallylamine polymer; a resin having a secondary amine such as a diallylamine polymer or polyethyleneimine; polyvinylamine, polyallylamine, polyornithine, polylysine And resins having a primary amine such as chitosan. Among these, a resin having a primary amine is preferable from the viewpoint of adhesion to the gas barrier layer, and polyvinylamine, polyallylamine, and chitosan are more preferable. These cationic resins can be modified as long as the object of the present invention is not hindered, and may be an anionic salt. The kind of salt is not particularly limited. However, it is preferable that the multilayer film of the present invention is not salted.

  The overcoat layer preferably contains 5 to 100 parts by mass of a resin containing a hydroxyl group, more preferably 10 to 80 parts by mass, and more preferably 20 to 60 parts by mass with respect to 100 parts by mass of the cationic resin. More preferably. Examples of the resin containing a hydroxyl group include polyvinyl alcohol, modified polyvinyl alcohol, and saccharides. Examples of the modified polyvinyl alcohol include an ethylene-vinyl alcohol copolymer; polyvinyl alcohol modified with a carbonyl group, an ether group, a carboxylic acid, or the like. Of these, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferable.

The overcoat layer may be added with an anti-blocking agent such as stearic acid amide or oleic acid amide as long as the object of the present invention is not impaired.
The overcoat layer is substantially free of a curing agent that reacts with the cationic resin, that is, is formed by coating a liquid that does not contain a curing agent that reacts with the cationic resin on the gas barrier layer. Is preferred. When a curing agent that reacts with the cationic resin is included, the blocking tends to be improved, but the heat seal strength is reduced.

  In the present invention, “does not contain” a curing agent that reacts with a cationic resin has both meanings that it does not contain at all and that it contains a trace amount so that the heat seal strength does not decrease.

  Examples of the curing agent that reacts with the cationic resin, which is preferably substantially free, include isocyanates, epoxies, and polycarboxylic acids. As described above, in the present invention, it is preferable that these compounds are not contained in the liquid for forming the overcoat layer.

  Examples of the solvent for applying the overcoat layer on the gas barrier layer include water, alcohols (such as methanol, ethanol, propanol, isopropanol, ethylene glycol, and diethylene glycol), dimethylformamide, dimethyl sulfoxide, and acetone. In particular, water, alcohol, and a water-alcohol mixture are preferable. Although the preparation method of a coating liquid is not specifically limited, After dissolving resin for forming an overcoat layer in water, the method of diluting with alcohol is preferable.

  As the adhesive layer, known adhesives such as acrylic, urethane and ester can be used. Of these, urethane-isocyanate two-component adhesives are preferable in terms of adhesiveness. The solvent used for the adhesive may be water or an organic solvent.

  As the resin constituting the sealant layer, low density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-4-methyl -1-pentene copolymer, ethylene-octene copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer And polyolefin resins such as ionomer resins; polyacrylonitrile resins; polyester resins and the like.

  In producing the multilayer film of the present invention, the method of providing an anchor coat layer, a gas barrier layer, an overcoat layer, and an adhesive layer on the surface of the base material layer is not particularly limited. For example, a direct gravure method , Reverse gravure method, microgravure method and other gravure methods; two roll beat coating method, bottom feed three reverse coating method and other roll coating methods; doctor knife method; die coating method; bar coating method; Can be used.

  In the multilayer film of the present invention, printing can be performed by a known method as necessary on the overcoat layer or on the non-coated surface on which the gas barrier layer or the like is not provided on the substrate.

  When producing the multilayer film of the present invention, an anchor coat layer is provided on the base material layer by the method as described above, and then a dispersion for forming a gas barrier layer is applied and dried to volatilize the dispersion medium. Then, the overcoat layer is formed by applying and drying a coating solution containing a cationic resin on the gas barrier layer by the method described above. In the case of printing, the multilayer film of the present invention can be obtained by printing on the non-coated surface or overcoat layer of the base material, applying the adhesive, and laminating the sealant layer. When not printing, the multilayer film of the present invention can be obtained by laminating a sealant layer after applying an adhesive on the overcoat layer.

  The method for laminating the sealant layer on the adhesive layer is not particularly limited. A method for extruding and laminating the resin constituting the sealant layer on the adhesive layer, and a film for forming the sealant layer on the adhesive layer. Examples include a method of dry lamination. The interface between the sealant layer and the overcoat layer may be subjected to treatment such as corona treatment, ozone treatment, electron beam treatment, and application of an anchor coat agent.

  When it has an anchor coat layer between a base material layer and a gas barrier layer, it is preferable that the thickness is 0.01-5 micrometers. The thickness of the gas barrier layer after drying is preferably about 0.01 μm to 10 μm. The thickness of the overcoat layer after drying is preferably 0.05 to 5 μm, and more preferably 0.1 to 1 μm. The thickness of the adhesive layer is preferably 0.1 to 5 μm. The thickness of the sealant layer after drying is preferably 0.001 μm or more from the viewpoint of heat seal strength, and is preferably 10 μm or less from the viewpoint of economy.

  Heat treatment of the multilayer film at 110 ° C. or higher and 220 ° C. or lower is preferable from the viewpoint of improving the gas barrier properties after the hot water treatment. The heat source used for the heat treatment is not particularly limited, and various methods such as hot roll contact, heat medium contact (air, etc.), infrared heating, microwave heating and the like can be applied.

  Each layer which comprises the multilayer film of this invention may contain various additives, such as a ultraviolet absorber, a coloring agent, and antioxidant, as needed to such an extent that the effect of this invention is not impaired. Moreover, the multilayer film of this invention may have layers other than the layer mentioned above.

The multilayer film of the present invention is excellent in heat sealability and gas barrier properties. For example, as a gas barrier property, an oxygen permeability at 20 ° C. and 50% RH can be 20 ml / m ² · day · MPa or less.

  Such a multilayer film of the present invention can be suitably used as a packaging material in many fields such as the food field, cosmetic field, agricultural chemical field, and medical field. In particular, it can be preferably used as a packaging bag.

Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these.
The measurement methods and evaluation methods for various physical properties in the following examples and comparative examples are as follows.

[Thickness]
The thickness of 0.5 μm or more was measured with a commercially available digital thickness meter (Nippon Optical Co., Ltd. contact-type thickness meter, trade name: Ultra High Precision Deci-Microhead MH-15M). On the other hand, the thickness of less than 0.5 μm was determined from the calibration curve by creating a calibration curve between the actual coating thickness and IR absorption by the IR method.

[Particle size of inorganic layered compound]
Using a laser diffraction / scattering type particle size distribution measuring device (LA910, manufactured by Horiba, Ltd.), the volume-based median diameter of particles considered to be an inorganic layered compound present in polyvinyl alcohol was measured as the particle size. In addition, in the case of the dispersion liquid stock solution containing polyvinyl alcohol and the inorganic layered compound, the measurement was performed with a paste cell at an optical path length of 50 μm. In the case of the diluted solution of this dispersion, the measurement was performed at an optical path length of 4 mm by the flow cell method.

[Aspect ratio of inorganic layered compound]
Using an X-ray diffractometer (manufactured by Shimadzu Corporation, XD-5A), the inorganic layered compound alone and the dried coating liquid containing polyvinyl alcohol and the inorganic layered compound were determined by diffraction measurement by a powder method. Thereby, the unit thickness a of the inorganic layered compound was determined. Furthermore, it was confirmed from the diffraction measurement about what dried the coating liquid which forms a gas barrier layer that there exists a part which the surface interval of an inorganic layered compound has spread. Using the particle size L determined by the above method, the aspect ratio Z is
Z = L / a
It was calculated by the following formula.

[Oxygen permeability]
Based on JIS K7126, the measurement was performed under the conditions of 23 ° C. and 50% RH using an ultrasensitive oxygen permeability measuring device (manufactured by MOCON, OX-TRANML).

[Heat seal strength]
The sealant layers of the two multilayer films were overlapped with each other and pressed with a heat press machine at a sealing pressure of 9.8 N (1 kg / cm ² ) for 1 second under the temperature conditions of an upper part of 160 ° C. and a lower part of 130 ° C. This sample was cut out with a width of 15 mm, and one day later, a T-type peel test was conducted using a tensile tester (manufactured by Intesco, precision universal material tester type 2020) at a distance between chucks of 1 cm and a pulling speed of 300 mm / min. The strength was evaluated. A heat seal strength of 30 N or more was evaluated as good and indicated by ◯, and a value less than 30 N was evaluated as poor and indicated by x.

[Example 1]
A dispersion kettle (made by Asada Tekko Co., Ltd., trade name: Despa MH-L), ion-exchanged water (specific electrical conductivity 0.7 μs / cm or less) 1300 g, polyvinyl alcohol (Kuraray Co., Ltd., PVA117H, saponification degree 99. 6%, polymerization degree 1,700) and 130 g were mixed, and the temperature was raised to 95 ° C. under low speed stirring (1500 rpm, peripheral speed 4.1 m / min). The mixed system was stirred at the same temperature for 30 minutes to dissolve the polyvinyl alcohol, and then cooled to 60 ° C. to obtain an aqueous polyvinyl alcohol solution.

While stirring this polyvinyl alcohol aqueous solution (60 ° C.) under the same conditions as described above, 122 g of 1-butanol, 122 g of isopropyl alcohol and 520 g of ion-exchanged water were mixed, and the alcohol aqueous solution obtained thereby was dropped over 5 minutes. did. After completion of the dropping, switching to high speed stirring (3000 rpm, peripheral speed = 8.2 m / min), gradually adding 65 g of high purity montmorillonite (Kunimine Kogyo Co., Ltd., trade name: Kunipia G) to the stirring system, Stirring was continued at 60 ° C. for 60 minutes. Thereafter, 243 g of isopropanol was further added over 15 minutes, and then the mixed system was cooled to room temperature to obtain a dispersion liquid (1) containing montmorillonite as an inorganic layered compound and polyvinyl alcohol. 0.1 part by mass of nonionic surfactant (polydimethylsiloxane-polyoxyethylene copolymer; manufactured by Toray Dow Corning Co., Ltd., trade name: SH3746) with respect to this dispersion (1) (dispersion (1) (Based on mass) and further using a high-pressure disperser (trade name: Super High Pressure Homogenizer M110-E / H, manufactured by Microfluidics Corporation) under the conditions of 10.8 kN / cm ² (1100 kgf / cm ² ). To obtain a dispersion (2) containing montmorillonite as an inorganic layered compound and polyvinyl alcohol.

  The average particle diameter of the cleaved montmorillonite at this time was 560 nm, the unit length obtained from powder X-ray diffraction, that is, the a value was 1.2156 nm, and the aspect ratio was 460.

  To 2000 g of the dispersion (2) containing montmorillonite and polyvinyl alcohol as the inorganic layered compound, 5.33 g of titanium acetylacetonate (manufactured by Matsumoto Pharmaceutical Co., Ltd., trade name: TC100) as a chelate compound is stirred at a low speed (1500 rpm). Under a peripheral speed of 4.1 m / min), a dispersion containing polyvinyl alcohol, montmorillonite as an inorganic layered compound, and a chelate compound by gradually adding while adjusting with hydrochloric acid so that the pH of the system is 3 or less (3) was prepared.

  A biaxially stretched nylon (ON) film (product name: Emblem ON-U, manufactured by Unitika Co., Ltd.) having a thickness of 15 μm and subjected to double-side corona treatment was used as a base material layer (base material film). Then, on one surface of the base film, an anchor coating agent (manufactured by Toyo Morton, EL510-1 / CAT-RT87 = 5/1 [mass ratio]) and a test coater (manufactured by Yasui Seiki Co., Ltd.) By using the microgravure coating method, gravure coating was performed at a coating speed of 3 m / min and a drying temperature of 80 ° C. to form an anchor coat layer. The dry thickness of this anchor coat layer was 0.05 μm.

  Furthermore, the dispersion liquid (3) containing the above-mentioned polyvinyl alcohol, montmorillonite as an inorganic layered compound, and a chelate compound was applied by a micro gravure coating method using a test coater (manufactured by Yasui Seiki Co., Ltd.), Gravure coating was performed at a drying temperature of 100 ° C. to obtain a coated film in which a film (gas barrier layer) based on the upper dispersion (3) was formed on the base material layer via an anchor coat layer. The film thickness (dry thickness) of the gas barrier layer was 0.2 μm.

  Next, the coating liquid was applied onto the gas barrier layer of the coating film to form an overcoat layer. For the coating solution, polyallylamine (manufactured by Nittobo Co., Ltd., trade name: PAA-H-10C) / polyvinyl alcohol (the above-mentioned PVA117H) = 100/40 [mass ratio]), solid content of 10% by mass was used. This coating liquid was subjected to gravure coating at a coating speed of 3 m / min and a drying temperature of 100 ° C. by a micro gravure coating method using a test coater (manufactured by Yasui Seiki Co., Ltd.) to form an overcoat layer. The dry thickness of this overcoat layer was 0.2 μm.

  Next, a linear low density polyethylene whose surface is corona-treated with a urethane adhesive (TM250 / CAT-RT86-60L = 15/2 (mass ratio) manufactured by Toyo Morton Co., Ltd.) on the overcoat layer. (Tosero Co., Ltd., trade name: TUX-FCD, thickness 70 μm) was dry laminated as a sealant layer to obtain a multilayer film.

  The multilayer film was measured for gas barrier properties and heat seal strength. The results are shown in Table 1. As shown in Table 1, this multilayer film was excellent in gas barrier properties and heat seal strength.

[Examples 2 and 3]
Instead of the dispersion (3) containing polyvinyl alcohol, the montmorillonite as the inorganic layered compound, and the chelate compound in Example 1, a dispersion (2) containing the montmorillonite as the polyvinyl alcohol and the inorganic layered compound and not containing the chelate compound Was used. The mass ratio of polyallylamine and polyvinyl alcohol in the overcoat layer was changed as shown in Table 1. Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, these multilayer films were excellent in gas barrier properties and heat seal strength.

Example 4
The base film of Example 1 was replaced with a 12 μm-thick biaxially stretched polyethylene terephthalate film (product name: Emblet PET12) manufactured by Unitika Co., Ltd., and the anchor coating agent (Dainippon Ink Co., Ltd., LX-747A / Instead of polyvinyl alcohol as an overcoat agent, an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., trade name: AQ-4105) was used instead of KX-75 = 7/1 [mass ratio]. Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, this multilayer film was excellent in gas barrier properties and heat seal strength.

Example 5
Chitosan was used instead of polyallylamine in the overcoat agent of Example 1, and ethylene-vinyl alcohol (AQ-4105) was used instead of the polyvinyl alcohol. Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, this multilayer film was excellent in gas barrier properties and heat seal strength.

Example 6
Polyvinyl alcohol (PVA117H described above) was dissolved in pure water to obtain a 10% by mass aqueous solution. An ethylene-maleic acid alternating copolymer (manufactured by ALDRICH, weight average molecular weight 100,000 to 500,000) is dissolved in water containing 5 mol% sodium hydroxide based on the carboxyl group of maleic acid, and 10 mass % Aqueous solution. And both aqueous solution was mixed so that mass ratio of polyvinyl alcohol and an ethylene-maleic acid copolymer might be set to (polyvinyl alcohol) / (ethylene-maleic acid copolymer) = 70/30. Subsequently, the inorganic layered compound (montmorillonite, manufactured by Kunimine Kogyo Co., Ltd., trade name: Kunipia F) is 10 parts by mass with respect to a total of 100 parts by mass of the solid content of the polyvinyl alcohol and the ethylene-maleic acid copolymer. And stirred to prepare a dispersion. Furthermore this above high-pressure dispersion apparatus (Microfluidics Corporation, trade name: Ultra-high pressure homogenizer M110-E / H) ^using, treated with the conditions of 10.8kN / cm 2 (1100kgf / cm 2), the inorganic layered compound As a result, a dispersion (4) containing montmorillonite and polyvinyl alcohol was obtained.

  Polyvinyl alcohol, ethylene-maleic acid copolymer, and montmorillonite as an inorganic layered compound instead of the polyvinyl alcohol, montmorillonite as an inorganic layered compound, and the dispersion (3) containing a chelate compound in Example 1. A gas barrier layer was formed using a dispersion (4) containing Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, this multilayer film was excellent in gas barrier properties and heat seal strength.

[Comparative Example 1]
Compared to Example 1, no overcoat layer was formed. Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, this multilayer film was inferior in heat sealability.

[Reference Example 1]
Compared with Example 1, as a coating liquid for the overcoat layer, instead of polyallylamine / polyvinyl alcohol of Example 1, polyallylamine / isocyanate (BASF, trade name: HW-100) 100/10 (mass ratio) ), 10 mass% solid content was used. Other than that was carried out similarly to Example 1, and obtained the multilayer film. The evaluation results of the obtained multilayer film are shown in Table 1.

  As shown in Table 1, this multi-layer film was inferior in heat sealability because the overcoat layer contained isocyanate as a curing agent that reacts with the cationic resin.

Claims (11)

  A gas barrier layer formed by applying a dispersion containing an inorganic stratiform compound and a water-soluble polymer on at least one surface of a base material layer composed of a thermoplastic resin, and has a cationic resin and a hydroxyl group An overcoat layer containing a resin, an adhesive layer, and a sealant layer are sequentially laminated.   The multilayer film according to claim 1, wherein the overcoat layer does not contain a curing agent that reacts with the cationic resin.   The multilayer film according to claim 1 or 2, wherein the cationic resin contained in the overcoat layer contains a primary amine.   The multilayer film according to any one of claims 1 to 3, wherein the overcoat layer contains 5 to 100 parts by mass of a hydroxyl group-containing resin with respect to 100 parts by mass of the cationic resin. .   The multilayer film according to any one of claims 1 to 4, wherein the resin having a hydroxyl group contained in the overcoat layer is polyvinyl alcohol or modified polyvinyl alcohol.   6. The multilayer film according to any one of claims 1 to 5, wherein the cationic resin contained in the overcoat layer is polyallylamine or chitosan.   The multilayer film according to any one of claims 1 to 6, wherein an anchor coat layer is provided between the base material layer and the gas barrier layer.   The multilayer film according to any one of claims 1 to 7, wherein the water-soluble polymer contained in the gas barrier layer contains at least one of a hydroxyl group and a carboxyl group.   The multilayer film according to any one of claims 1 to 8, wherein the adhesive layer contains isocyanate. 10. The multilayer film according to claim 1, wherein the oxygen permeability at 20 ° C. and 50% RH is 20 ml / m ² · day · MPa or less.   It is comprised with the multilayer film of any one of Claim 1-10, The packaging bag characterized by the above-mentioned.